A mobile communication system is provided for increasing the capacity for personal stations and ensuring a radio channel for use with a micro cellular system irrespective of the environment in which the system is installed. In the mobile communication system which allows the coexistence of a cellular automobile telephone system and a micro cellular system, communications in the cellular automobile telephone systems and the micro cellular systems are performed in a digital form, and a personal station accessing to each of these systems is connected thereto by using a time-division multiplex access mode or a code division multiplex access mode. Since the time-division multiplex access mode or code division multiplex access mode is used, a radio channel at the same frequency can be used by a plurality of personal stations. Thus, the capacity of the system can be increased for personal stations without extending a used frequency band.